(a) Field of the Invention
The present invention relates to an Inkjet head and an ink supplying method.
(b) Description of the Related Art
Generally, various thin film patterns of flat panel displays such as a liquid crystal display (LCD) and an organic light emitting diode (OLED) display are formed through a photolithography process. A large flat panel display uses more materials during manufacturing, such as a photosensitive film that is applied on a substrate to form a thin film pattern. Moreover, much larger manufacturing equipment for a photolithography process may also be needed. This usually results in increased manufacturing costs.
In order to minimize the cost increase, an Inkjet printing system to form a thin film pattern by dripping ink has been developed. This Inkjet printing system includes an inkjet printing main body and an inkjet head having a plurality of nozzles, whereby the ink is dripped with a uniform volume through the nozzles of the inkjet head in a predetermined region on the substrate.
The Inkjet head comprises an ink storage unit and a head unit. When the ink stored in an ink storage unit of the Inkjet head is supplied to the head unit through two injection holes, most of the air is discharged through the nozzles; however, the vapor that is not discharged is confined in the flow space of the head unit. This vapor closes the flow path of the nozzles while flowing, such that abnormal discharge may be generated. Although pressure is applied to the ink to push the vapor, the pressure applied to the surface of the ink stored inside the ink storage unit acts on two injection holes with an equal magnitude, with the result that the vapor is not pushed in the predetermined direction in the flow space inside the head unit.
To remove the vapor, a structure in which the ink storage unit is connected to the head unit through only one injection hole, and an additional discharge unit is installed to the head unit, has been proposed. In this structure, the vapor may be discharged through the additional discharge unit along with the ink. However, a valve is necessary in this case, and as a controller and a device to shut off the valve are required, a large quantity of ink is consumed. Also, the injection hole is positioned on one side of the ink storage unit, such that the flow resistance is changed according to the position of the nozzle, resulting in a non-uniform discharge amount.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention; therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.